1. Field of the Invention
The present invention relates to a musical instrument, more especially to a hinge tube of a wind instrument.
2. Description of the Prior Art
A wind instrument, especially a saxophone or other woodwind instrument, produces tones with different frequency by opening or shutting the tone holes on the instrument to change the effective length of the instrument. To make controlling each tone hole easier, a hinge tube and valves are disposed on a plurality of instruments, as disclosed in TW 371096, TW 371097, TW M420798, and U.S. Pat. No. 7,608,768. The keys drive the hinge tube to rotate, and the valves fixed to the hinge tube also rotate and open or shut the tone holes.
The hinge tubes disclosed in the patents mentioned above are principally circular rods or polygonal rods, and the valves are fixed on the hinge tube. Due to the simple shape and the smooth surface of the hinge tube, the valves are fixed unstably frequently. Moreover, a maker can not confirm the positions to which the valves should be fixed when manufacturing. The positions of valves have to be confirmed over and over, and the efficiency of manufacture is low.
The present invention, therefore, makes improvements on the disadvantages as mentioned above.